A comparative study of precursor effect on manganese post-synthetic incorporation into the T-sites of dealuminated beta-zeolite

作者：Hayek Naseem S; Lucas Nishita S; Damouny Christine Warwar; Gazit Oz M

来源：Microporous and Mesoporous Materials, 2017, 244: 31-36.

DOI：10.1016/j.micromeso.2017.02.037

• Beta zeolite
• Dealumination
• Manganese
• Acetate
• Nitrate

Manganese sites on zeolites are known to be catalytically active for a range of chemical reactions. The work here describes the post-synthetic incorporation of manganese (Mn) into the vacant silanol nests of 0-zeolite. We show that markedly different material properties are obtained when the Mn(NO3)(2) precursor is used as opposed to the Mn(Ac)(2) precursor. Our DRIFT and XRD results show that the Mn(NO3)(2) does not promote the incorporation of the Mn into the vacant silanol nests. Rather we find, by XRD and HRSEM, that the Mn(NO3)(2) leads to the formation of poorly dispersed 14 t 1 nm MnO2 crystals on the external surface of the dealuminated 3-zeolite. On the contrary, when Mn(Ac)(2) is used the XRD and DRIFT results clearly show the almost complete incorporation of Mn into the silanol nests and a significant effect on the microporous structure. HRSEM. DR-UV-Vis. H-2-TPR and N-2-physisorption show that the use of Mn(Ac)(2) produces highly dispersed extra-framework Mn2O3 and Mn3O4 species inside and outside the pores of the dealuminated zeolite, where as in the case of Mn(NO3)(2) the pores maintain their original properties. The difference in behavior between the two precursors is correlated to the intrinsic properties of the respective precursor and its interactions with the underlying zeolite support.

• 出版日期2017-5-15